The figure shows an empty rectangular tank with a capacity of 87 ℓ. The tank has a height of 29 cm. Tap H filled the tank at a rate of 3 ℓ per minute. Tap J drained water from the tank at a rate of 1.8 ℓ per minute. Both taps were turned on for 28 minutes and then turned off.
- What is the base area of the tank?
- After both taps were turned off, how much more water is needed to fill the tank completely? Give your answer in litres.
(a)
1 ℓ = 1000 mℓ
87 ℓ = 87 x 1000 = 87000 mℓ
Base area of the tank
=
Volumeheight =
8700029 = 3000 cm
2 (b)
Volume of water that filled the tank per minute when both taps were turned on
= 3 - 1.8
= 1.2 ℓ
Volume of water that filled the tank in 28 minutes when both taps were turned on
= 28 x 1.2
= 33.6 ℓ
Volume of water needed to fill the tank
= 87 - 33.6
= 53.4 ℓ
Answer(s): (a) 3000 cm
2; (b) 53.4 ℓ